#include "string.h"
#include "md_5.h"

unsigned char PADDING[] = { 0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
			    0,	  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
			    0,	  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
			    0,	  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

void md5_init(MD5_CTX_T *context)
{
	context->count[0] = 0;
	context->count[1] = 0;
	context->state[0] = 0x67452301;
	context->state[1] = 0xEFCDAB89;
	context->state[2] = 0x98BADCFE;
	context->state[3] = 0x10325476;
}
void md5_update(MD5_CTX_T *context, unsigned char *input, unsigned int inputlen)
{
	unsigned int i = 0, index = 0, partlen = 0;

	index = (context->count[0] >> 3) & 0x3F;
	partlen = 64 - index;
	context->count[0] += inputlen << 3;
	if (context->count[0] < (inputlen << 3))
		context->count[1]++;
	context->count[1] += inputlen >> 29;

	if (inputlen >= partlen) {
		memcpy(&context->buffer[index], input, partlen);
		md5_transform(context->state, context->buffer);
		for (i = partlen; i + 64 <= inputlen; i += 64)
			md5_transform(context->state, &input[i]);
		index = 0;
	} else {
		i = 0;
	}
	memcpy(&context->buffer[index], &input[i], inputlen - i);
}
void md5_final(MD5_CTX_T *context, unsigned char digest[16])
{
	unsigned int index = 0, padlen = 0;
	unsigned char bits[8];

	index = (context->count[0] >> 3) & 0x3F;
	padlen = (index < 56) ? (56 - index) : (120 - index);
	md5_encode(bits, context->count, 8);
	md5_update(context, PADDING, padlen);
	md5_update(context, bits, 8);
	md5_encode(digest, context->state, 16);
}
void md5_encode(unsigned char *output, unsigned int *input, unsigned int len)
{
	unsigned int i = 0, j = 0;

	while (j < len) {
		output[j] = input[i] & 0xFF;
		output[j + 1] = (input[i] >> 8) & 0xFF;
		output[j + 2] = (input[i] >> 16) & 0xFF;
		output[j + 3] = (input[i] >> 24) & 0xFF;
		i++;
		j += 4;
	}
}
void md5_decode(unsigned int *output, unsigned char *input, unsigned int len)
{
	unsigned int i = 0, j = 0;

	while (j < len) {
		output[i] = (input[j]) |
			    (input[j + 1] << 8) |
			    (input[j + 2] << 16) |
			    (input[j + 3] << 24);
		i++;
		j += 4;
	}
}
void md5_transform(unsigned int state[4], unsigned char block[64])
{
	unsigned int a = state[0];
	unsigned int b = state[1];
	unsigned int c = state[2];
	unsigned int d = state[3];
	unsigned int x[64];

	md5_decode(x, block, 64);
	FF(a, b, c, d, x[0], 7, 0xd76aa478);    /* 1 */
	FF(d, a, b, c, x[1], 12, 0xe8c7b756);   /* 2 */
	FF(c, d, a, b, x[2], 17, 0x242070db);   /* 3 */
	FF(b, c, d, a, x[3], 22, 0xc1bdceee);   /* 4 */
	FF(a, b, c, d, x[4], 7, 0xf57c0faf);    /* 5 */
	FF(d, a, b, c, x[5], 12, 0x4787c62a);   /* 6 */
	FF(c, d, a, b, x[6], 17, 0xa8304613);   /* 7 */
	FF(b, c, d, a, x[7], 22, 0xfd469501);   /* 8 */
	FF(a, b, c, d, x[8], 7, 0x698098d8);    /* 9 */
	FF(d, a, b, c, x[9], 12, 0x8b44f7af);   /* 10 */
	FF(c, d, a, b, x[10], 17, 0xffff5bb1);  /* 11 */
	FF(b, c, d, a, x[11], 22, 0x895cd7be);  /* 12 */
	FF(a, b, c, d, x[12], 7, 0x6b901122);   /* 13 */
	FF(d, a, b, c, x[13], 12, 0xfd987193);  /* 14 */
	FF(c, d, a, b, x[14], 17, 0xa679438e);  /* 15 */
	FF(b, c, d, a, x[15], 22, 0x49b40821);  /* 16 */

	/* Round 2 */
	GG(a, b, c, d, x[1], 5, 0xf61e2562);    /* 17 */
	GG(d, a, b, c, x[6], 9, 0xc040b340);    /* 18 */
	GG(c, d, a, b, x[11], 14, 0x265e5a51);  /* 19 */
	GG(b, c, d, a, x[0], 20, 0xe9b6c7aa);   /* 20 */
	GG(a, b, c, d, x[5], 5, 0xd62f105d);    /* 21 */
	GG(d, a, b, c, x[10], 9, 0x2441453);    /* 22 */
	GG(c, d, a, b, x[15], 14, 0xd8a1e681);  /* 23 */
	GG(b, c, d, a, x[4], 20, 0xe7d3fbc8);   /* 24 */
	GG(a, b, c, d, x[9], 5, 0x21e1cde6);    /* 25 */
	GG(d, a, b, c, x[14], 9, 0xc33707d6);   /* 26 */
	GG(c, d, a, b, x[3], 14, 0xf4d50d87);   /* 27 */
	GG(b, c, d, a, x[8], 20, 0x455a14ed);   /* 28 */
	GG(a, b, c, d, x[13], 5, 0xa9e3e905);   /* 29 */
	GG(d, a, b, c, x[2], 9, 0xfcefa3f8);    /* 30 */
	GG(c, d, a, b, x[7], 14, 0x676f02d9);   /* 31 */
	GG(b, c, d, a, x[12], 20, 0x8d2a4c8a);  /* 32 */

	/* Round 3 */
	HH(a, b, c, d, x[5], 4, 0xfffa3942);    /* 33 */
	HH(d, a, b, c, x[8], 11, 0x8771f681);   /* 34 */
	HH(c, d, a, b, x[11], 16, 0x6d9d6122);  /* 35 */
	HH(b, c, d, a, x[14], 23, 0xfde5380c);  /* 36 */
	HH(a, b, c, d, x[1], 4, 0xa4beea44);    /* 37 */
	HH(d, a, b, c, x[4], 11, 0x4bdecfa9);   /* 38 */
	HH(c, d, a, b, x[7], 16, 0xf6bb4b60);   /* 39 */
	HH(b, c, d, a, x[10], 23, 0xbebfbc70);  /* 40 */
	HH(a, b, c, d, x[13], 4, 0x289b7ec6);   /* 41 */
	HH(d, a, b, c, x[0], 11, 0xeaa127fa);   /* 42 */
	HH(c, d, a, b, x[3], 16, 0xd4ef3085);   /* 43 */
	HH(b, c, d, a, x[6], 23, 0x4881d05);    /* 44 */
	HH(a, b, c, d, x[9], 4, 0xd9d4d039);    /* 45 */
	HH(d, a, b, c, x[12], 11, 0xe6db99e5);  /* 46 */
	HH(c, d, a, b, x[15], 16, 0x1fa27cf8);  /* 47 */
	HH(b, c, d, a, x[2], 23, 0xc4ac5665);   /* 48 */

	/* Round 4 */
	II(a, b, c, d, x[0], 6, 0xf4292244);    /* 49 */
	II(d, a, b, c, x[7], 10, 0x432aff97);   /* 50 */
	II(c, d, a, b, x[14], 15, 0xab9423a7);  /* 51 */
	II(b, c, d, a, x[5], 21, 0xfc93a039);   /* 52 */
	II(a, b, c, d, x[12], 6, 0x655b59c3);   /* 53 */
	II(d, a, b, c, x[3], 10, 0x8f0ccc92);   /* 54 */
	II(c, d, a, b, x[10], 15, 0xffeff47d);  /* 55 */
	II(b, c, d, a, x[1], 21, 0x85845dd1);   /* 56 */
	II(a, b, c, d, x[8], 6, 0x6fa87e4f);    /* 57 */
	II(d, a, b, c, x[15], 10, 0xfe2ce6e0);  /* 58 */
	II(c, d, a, b, x[6], 15, 0xa3014314);   /* 59 */
	II(b, c, d, a, x[13], 21, 0x4e0811a1);  /* 60 */
	II(a, b, c, d, x[4], 6, 0xf7537e82);    /* 61 */
	II(d, a, b, c, x[11], 10, 0xbd3af235);  /* 62 */
	II(c, d, a, b, x[2], 15, 0x2ad7d2bb);   /* 63 */
	II(b, c, d, a, x[9], 21, 0xeb86d391);   /* 64 */
	state[0] += a;
	state[1] += b;
	state[2] += c;
	state[3] += d;
}
